pc wont run or open any programs

i built my first pc,
it was wrokign fine for the first 3 days.
all of a sudden i cant open anything i tried a system restore.
i tried going into safemode and downloading malwarebytes and doign a scan it found i think 7 items, i got rid of them still not working!
i really need help on how to fix this.
im new to this stuff aswell so if you could dumb down the troubleshooting i would apreciate it